alternate in const generics

src/gpio.rs

@@ -60,17 +60,17 @@ pub enum SignalEdge {
     RisingFalling,
 }
 
-#[allow(dead_code)]
-pub(crate) enum AltFunction {
-    AF0 = 0,
-    AF1 = 1,
-    AF2 = 2,
-    AF3 = 3,
-    AF4 = 4,
-    AF5 = 5,
-    AF6 = 6,
-    AF7 = 7,
-}
+/// Altername Mode (type state)
+pub struct Alternate<const A: u8>;
+
+pub const AF0: u8 = 0;
+pub const AF1: u8 = 1;
+pub const AF2: u8 = 2;
+pub const AF3: u8 = 3;
+pub const AF4: u8 = 4;
+pub const AF5: u8 = 5;
+pub const AF6: u8 = 6;
+pub const AF7: u8 = 7;
 
 /// External Interrupt Pin
 pub trait ExtiPin {
@@ -487,9 +487,8 @@ macro_rules! gpio {
                         self
                     }
 
-                    #[allow(dead_code)]
-                    pub(crate) fn set_alt_mode(&self, mode: AltFunction) {
-                        let mode = mode as u32;
+                    pub fn into_alternate<const A: u8>(self) -> $PXi<Alternate<A>> {
+                        let mode = A as u32;
                         let offset = 2 * $i;
                         let offset2 = 4 * $i;
                         unsafe {
@@ -508,6 +507,7 @@ macro_rules! gpio {
                                 w.bits((r.bits() & !(0b11 << offset)) | (0b10 << offset))
                             });
                         }
+                        $PXi { _mode: PhantomData }
                     }
                 }
 

src/rcc/clockout.rs

@@ -5,7 +5,7 @@ use crate::stm32::RCC;
 pub type LscoPin = gpioa::PA2<DefaultMode>;
 
 pub struct Lsco {
-    pin: LscoPin,
+    pin: gpioa::PA2<Alternate<AF0>>,
 }
 
 impl Lsco {
@@ -20,7 +20,7 @@ impl Lsco {
     }
 
     pub fn release(self) -> LscoPin {
-        self.pin
+        self.pin.into_floating_input()
     }
 }
 
@@ -30,7 +30,6 @@ pub trait LSCOExt {
 
 impl LSCOExt for LscoPin {
     fn lsco(self, src: LSCOSrc, rcc: &mut Rcc) -> Lsco {
-        self.set_alt_mode(AltFunction::AF0);
         let src_select_bit = match src {
             LSCOSrc::LSE => {
                 rcc.enable_lse(false);
@@ -43,7 +42,9 @@ impl LSCOExt for LscoPin {
         };
         rcc.unlock_rtc();
         rcc.rb.bdcr.modify(|_, w| w.lscosel().bit(src_select_bit));
-        Lsco { pin: self }
+        Lsco {
+            pin: self.into_alternate(),
+        }
     }
 }
 
@@ -65,7 +66,7 @@ impl<PIN> Mco<PIN> {
     }
 
     pub fn release(self) -> PIN {
-        self.pin
+        self.pin //TODO reverse pin to input<floating>
     }
 }
 
@@ -74,12 +75,10 @@ pub trait MCOExt<PIN> {
 }
 
 macro_rules! mco {
-    ($($PIN:ty),+) => {
+    ($($PIN:ident),+) => {
         $(
-            impl MCOExt<$PIN> for $PIN {
-                fn mco(self, src: MCOSrc, psc: Prescaler, rcc: &mut Rcc) -> Mco<$PIN> {
-                    self.set_alt_mode(AltFunction::AF0);
-
+            impl MCOExt<$PIN<Alternate<AF0>>> for $PIN<DefaultMode> {
+                fn mco(self, src: MCOSrc, psc: Prescaler, rcc: &mut Rcc) -> Mco<$PIN<Alternate<AF0>>> {
                     let psc_bits = match psc {
                         Prescaler::NotDivided => 0b000,
                         Prescaler::Div2 => 0b001,
@@ -114,11 +113,14 @@ macro_rules! mco {
                             0b111
                         },
                     };
-                    Mco { src_bits, pin: self }
+                    Mco { src_bits, pin: self.into_alternate() }
                 }
             }
         )+
     };
 }
 
-mco!(gpioa::PA8<DefaultMode>, gpiog::PG10<DefaultMode>);
+use crate::gpio::gpioa::PA8;
+use crate::gpio::gpiog::PG10;
+
+mco!(PA8, PG10);